The present invention relates to controllers and more particularly to hand operated controllers for operating remote systems such cranes, robot arms, air or space craft, free flyers and the like.
A number of hand controllers exist in the prior art designed for controlling robots, air craft or space craft and having specific features useful for particular applications. For example, in the Wyllie U.S Pat. No. 4,913,000, Wyllie U.S. Pat. No. 3,914,976 and the Hegg U.S. Pat. No. 4,895,039 all assigned to the assignee of the present invention, a wrist action hand grip for 3 degrees of freedom and a forearm grip for providing additional degrees of freedom is shown and has special utility in helicopter control. Cross coupling between the hand controller and the forearm controller is avoided by having the hand controller mounted on the same apparatus that carries the forearm apparatus so that motion of the forearm does not effect motion of the hand and vice versa. The hand controller itself is described in the Wyllie patents as a standard prior art device and such grips like that shown in U.S. Pat. No. 4,895,039 above, usually do not have all three of the axes passing through a common point. Accordingly, some cross coupling can occur about the offset axis. Furthermore, mounting the hand controller at the end of the forearm control box, as shown in the above mentioned patents, provides a rather lengthy control mechanism which, in a space craft, extends too far into the space occupied by the user than may be desired.
While hand controllers having all three axes passing through a common point located within the hand grip itself are not completely unknown in the prior art as, for example, U.S. Pat. No. 4,555,960 issued to Michael King on Dec. 3, 1985, such controllers are faced with other difficulties which make them impractical. For example, because a hand controller grip is limited in size so as to accommodate the human hand, it has been heretofore impossible to get all of the mechanism necessary for producing control outputs and force feedback inputs to control three different degrees of freedom with the desired "feel" all within the hand grip itself. In the above mentioned King patent, the yaw axis has an extension from the hand grip to a remote housing where a large enough force feedback device could be located, but with regard to pitch and roll, tiny scissor/spring mechanisms are shown within the hand grip itself to attempt to provide force feedback for the pitch and roll axes. Unfortunately, they are too small to work effectively which is always the case because electric torque generating motors and scissor/ spring mechanism large enough for such purposes are too large to fit within the hand grip. When attempts are made to locate the force producing motors or scissor/spring mechanisms remote from the hand grip so that they can be large enough to provide the desired "feel", the pitch and/or roll axes are then also remote from the hand grip with the result that the three axes do not intersect inside of the hand grip and cross coupling can occur.